SHETLAND OWNERS ASSOCIATION

Can anyone tell me the ideal chain/rope ratio for anchoring a 570 with normal boat clutter on a grapnel anchor. We are Solent based and only use our anchor in an emergancy situation ( the Bottom of the Solent is mud and sand). Our old anchor has given up the ghost and had 10 metres of 8mm chain with 50 metres of 10mm warp which seems excessive to me

thanks

This is a million dollar question, the last thing you want is for your anchor to start slipping, while you are asleep or ashore and begin its own voyage on its own. On small boats the general rule of thumb for the length of chain is, equivalent to or longer than your length of your boat, but the longer the better. As for the warp length this is calculated at the ratio of 1:5, so for every 1m in depth you should let out 5m of warp, so 50m of warp is good for a depth of 10m, this being said the longer the better up to a max ratio of 1:8 in stormy weather. Hope this helps.

ive just asked this question on the boating forum that i subscribe to sue, they say the anchor chain should be at least the lenght of the boat, plus some. but also say that 4m should suffice. cheers, alan

Was going to be all geeky but thought I'd let you read the original material

http://www.myboatsgear.com/newsletter/2008910.asp is all about anchors plus there also lots in the RYA Powerboating Level 2 course book

In short chain is there to keep from chafing on seabed and to keep anchor still. Weight of chain is equal to weight of anchor.

Overall lenght for Solent is approx 1:6 (water to warp) This can vary from 1:3 to 1:10 depending on personal preference

Final point is just how big is your anchor and would a plough anchor be better for sand and mud.

Hi all
As an old fool we use to use a large weight about 5mts from the anchor of the on the end of the chain this changed the angle of pull on the anchor , this held my boat ( 30ft sailing boat) off the Goodwin sands in a force 10 gale in the 60s. Morning cloud was lost in this storm. Not an experience that I wish to repeat. I hope this helps
Pete

An American site, but one I use for odd bits of info.
This is their take on anchoring:
http://www.boatsafe.com/nauticalknowhow/anchorsteps.htm